A motor vehicle may carry a freezable liquid in a dispenser. Examples of freezable liquids include water, windshield washer, and urea mixtures for use in emissions control. During operation, the motor vehicle may draw the liquid from the bottom of the dispenser. At low temperatures, however, the liquid may freeze to solid form and require thawing prior to being drawn out. Thus, in some applications, it may be advantageous to provide heat to the dispenser to thaw the solid, and thereby reclaim the liquid.
The rate of thawing may depend on the detailed geometry of the dispenser. Although a dispenser may be designed to have substantially parallel walls, various factors may cause the walls to be non-parallel. Finite dimensional tolerances of the dispenser, which arise during manufacturing, are one such factor. Another factor is that the dispenser may deform subsequent to manufacturing—because it is made of a pliable material or because of expansion, on freezing, of a liquid within it. If the walls taper even slightly inward from the top of the dispenser to the bottom, a frozen solid may be held up and be slow to reach a heated bottom portion of the dispenser. As the thawed liquid is drawn out, further thawing may be limited by convective heat transfer through an air-filled zone at the bottom portion. This effect may limit the rate at which liquid may be drawn from the dispenser.
Additionally, when a liquid is thawed in a container having substantially parallel walls, the remaining solid—if it is less dense than the liquid—may float to the top, and convective heat transfer from the bottom of the container to the frozen solid above may be slow. Therefore, U.S. Pat. No. 5,235,823 discloses a container in which ice is thawed to provide cooling, wherein the walls of the container taper outward from the top of the container to the bottom. In this container, the taper prevents ice from floating to the top of the liquid and thereby increases the rate of heat transfer.
In the cited reference, heat is transferred to the ice through the walls of the container. Additional problems may arise, however, if heat is provided by an immersion heater set in the container, and the container is disposed in a motor vehicle. In a motor vehicle, where vibration and acceleration may be significant, the possibility of unthawed solids moving freely within the container and contacting the immersion heater may be unacceptable. Further, the problem of the frozen portion floating to the top of the liquid may be irrelevant if the liquid is drawn out of the container and delivered elsewhere during the melting process.
The inventor herein has recognized the above problems and issues and has devised a series of approaches to address them. Thus, in one embodiment, a liquid dispenser is provided. The dispenser includes an exterior surface and an interior surface. The interior surface encloses a volume that tapers outwardly in a downward direction so that any horizontal cross-section of the volume fits inside each horizontal cross-section below it from a full to an empty level of the dispenser. The interior surface also includes a projection oriented opposite the exterior surface and configured to limit a motion of solids within the dispenser.
Another embodiment provides a system for delivering a liquid to a motor-vehicle component such as an exhaust-aftertreatment device. The system includes a liquid dispenser as described above and a conduit coupled to an opening at a bottom portion of the dispenser. The conduit is configured to conduct the liquid to the motor-vehicle component. The system also includes a heater operatively coupled to a controller and configured to heat at least the bottom portion of the dispenser.
The structure so provided enables the solid to slide to the heated, bottom portion of the dispenser as liquid is drawn from the dispenser. This configuration reduces limitations on the rate of thawing of the solid related to the rate of mass transport to the heated, bottom portion of the dispenser. Also, if the solid melts faster than the liquid is drawn from the dispense, the structure holds the solid portion down to increase heat transfer to the solid via the structure.
Other embodiments disclosed herein provide different variants of the dispenser, and methods for delivering a liquid to an exhaust-aftertreatment device in a motor-vehicle in accordance with the disclosed configurations.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the Detailed Description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.